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arXiv 2412.04556cond-mat.supr-concond-mat.quant-gascond-mat.stat-mechhep-thquant-ph
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弱监测约瑟夫森结阵列中的反向超导-绝缘体相变

Inverse Superconductor-Insulator Transition in Weakly Monitored Josephson Junction Arrays

Indian Institute of Science(印度科学学院)

Purnendu Das, Sumilan Banerjee

AI总结:

本研究通过弱监测和反馈在约瑟夫森结阵列中实现反向超导-绝缘体相变,揭示了量子反馈对非平衡稳态温度控制的作用。

摘要:

在开放量子系统中,通过测量和浴工程控制和操控量子态已成为许多体物理的新范式。在这里,以典型的约瑟夫森结阵列(JJAs)为例,我们展示如何通过连续弱测量和反馈重复监测,将这些系统中的绝缘态转变为超导态并反之。我们表明,即使在没有外部热浴的情况下,监测也会导致一个长期稳态,其特征由适当定义的 semiclassical 极限中的有效“量子”温度所描述。然而,我们表明,由于监测导致的量子耗散在 JJAs 与 Ohmic 浴接触的已研究情况下与平衡量子和/或热耗散有根本差异。特别是,通过变分近似,并考虑各种极限情况,我们证明这种差异可以导致重新进入的稳态相变,导致异常的反向相变,即从有效的低温绝缘正常态转变为中间温度的超导态。我们的工作强调了量子反馈的作用,它作为额外的调节器来控制非平衡稳态的有效温度,从而导致一个尚未在先前的监测和开放量子系统研究中探索过的相图。

英文摘要:

Control and manipulation of quantum states by measurements and bath engineering in open quantum systems have emerged as new paradigms in many-body physics. Here, taking a prototypical example of Josephson junction arrays (JJAs), we show how repetitive monitoring through continuous weak measurements and feedback can transform an insulating state in these systems to a superconductor and vice versa. We show that, even in the absence of any external thermal bath, the monitoring leads to a long-time steady state characterized by an effective `quantum' temperature in a suitably defined semiclassical limit. However, we show that the quantum dissipation due to monitoring has fundamental differences with equilibrium quantum and/or thermal dissipation in the well-studied case of JJAs in contact with an Ohmic bath. In particular, using a variational approximation, and by considering various limiting cases, we demonstrate that this difference can give rise to re-entrant steady-state phase transitions, resulting in unusual inverse transition from an effective low-temperature insulating normal state to superconducting state at intermediate temperature. Our work emphasizes the role of quantum feedback, that acts as an additional knob to control the effective temperature of non-equilibrium steady state leading to a phase diagram, not explored in earlier works on monitored and open quantum systems.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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